Golf clubs constituting the so-called "irons" comprise a series of clubs each club having a successively sloping striking surface which engages the golf ball. Thus, the golfer by using the same swing and force can vary the length of travel of the golf ball, depending upon the club that is selected, the higher numbered club having the greater slope to the ball striking surface. It is desirable that the ball striking surface of such clubs have high friction so that back spin is imparted to the golf ball at the time that it is struck so as to provide greater control over the ball after it has been hit so that the ball will attain the desired flight trajectory and the stopping or rolling distance of the ball will be minimized when desired.
At the present time this is accomplished by cutting grooves (usually horizontal) in the club head ball striking surface and decorative grit blasting or coating the surface with a hard particle bearing or plastic adhesive on the striking surface so as to provide greater friction between the ball and the striking surface at the moment of impact so as to impart backspin to the ball.
The disadvantage of golf club striking surfaces thus produced are that the friction surface has an extremely short life before it is worn down and the beneficial results are no longer achieved.
In the prior art there have been suggestions of adhering carbides and other hard particles to the striking surface of golf irons. For example, in Australian Pat. No. 268,181, Prince, et al., there is a disclosure of a metallic golf club head wherein a friction coating is placed on the striking surface of the golf club head using an epoxy resin, for example, in which powdered silicon, carbide, carborundum, etc. may be dispersed.
Japanese Pat. No. 52 26929, Miyama, discloses formation of a porous metal coating layer of metals of high melting point by the application of a plasma of flame-fusion process. Materials which may be used are metallic oxides, carbides, or silicides. On this layer a ceramic layer is added. The underlying layer must be porous in order successfully to bond to the ceramic layer. The porous ceramic layer then is immersed in a high elastic adhesive liquid plastic; for example, epoxy resin or polyurethane mixed with pigment to make it dry and hard.